The cover of the neck pickup is attached to the base of the pickup at all four corners, which you can't see under the scratchplate. Unscrewing the G side will not cause the pickup to come apart, although if you do unscrew it too much, you will run out of threads and have to go fishing or take the scratchplate off to re-thread the adjustment screw into the pickup. The screws on the E and G side are the same length, so you can go at least as far down on the G side as the E side started out.